With the continuous development of wireless communication industry, services for users to transmit data via a wireless network are increased gradually, and the existing available spectrum resources of operators become increasingly difficult to meet users' demands for data. In order to provide more wireless communications capacity for the users, a widely accepted solution is to use additional spectrum resources. While maintaining the use existing frequency band, the users can opportunistically use the additional spectrum resources, such as a television frequency band, a 5 GHz frequency band, to support the user's data communications.